Natural and Synthetic EDCs from Wastewater Treatment - source characterization, environmental fate, and risk management
Research Questions: Determine what are the major sources and environmental fates of EDCs natural and/or pharmaceutical additives. Determine how unreasonable risk can be managed. NRMRL's research program in risk management of endocrine disrupting chemicals (EDCs) is determining the efficacy of existing risk management approaches to minimize exposure to suspected EDCs and developing new risk management tools where needed. Research has shown certain chemicals are suspected to have the ability to disrupt the endocrine systems of mammals, birds, fish, reptiles, and other fauna. The scientific literature shows that certain chemicals can mimic or elicit effects similar to estrogens and other reproductive hormones. Reports in the literature also demonstrate that wildlife in surface water near wastewater treatment outfalls can show effects consistent with exposure to estrogenic compounds. Other reports show that certain suspected EDCs, especially natural and pharmaceutical hormones and estrogenic alkylphenols are commonly present in wastewater treatment effluents and associated surface waters. These compounds are removed to varying degrees during WW treatment and are therefore, commonly found in the effluents following wastewater treatment.
- Determine the fate of EDCs in conventional wastewater treatment plants.
- Determine if typical wastewater plant design and operational strategies maximize removal of EDCs.
- Determine the treatment capability of on-site wastewater treatment systems for EDCs.
- The research on evaluating both existing and innovative risk management strategies incorporates bench, pilot, and field scale investigations. Research has been conducted on the fate of alkylphenols and to characterize their biodegradation rates under redox conditions typically found in WWTPs. Additionally, research is being initiated to evaluate estrogenic and androgenic hormones under similar conditions.
- At the pilot scale, two pilot plants were constructed and operated to simulate a municipal WWTP. The plants were fed a simulated wastewater with constant dosing of EDCs to allow a mass balance analysis of the plant and the individual unit processes. Research has also been initiated at the full plant scale. A project evaluating the digesters efficacy has been initiated to study alkylphenols, hormones, and bisphenol A. This project is a collaborative effort between ORD laboratories, Region 5, and a regional wastewater utility.
- A second focus of this research is to determine techniques to optimize existing management strategies or develop alternative management strategies. Once unit operations and technology performance are understood, engineering solutions can be developed to reduce the EDCs discharge. Additional research is being developed in the areas of on-site WWT technologies. These technologies include septic systems, constructed wetlands, and other on-site technologies.
- Accomplishments to Date:
- Fate of EDCs in Conventional Wastewater Treatment Pilot Plants: The objective of this project was to determine the fate of reproductive hormones and alkylphenols throughout the plant unit processes for two common WWTP designs. Two pilot plants were built (one with anaerobic digestion, one with aerobic digestion) and are operating with EDCs in the feed. Analytical methods were developed to monitor these EDCs in the ēg/L level in all relevant matrices within the plants. EDC bioassays will also be employed to monitor the performance of the plants.
- Survey of Wastewater Treatment Plant Effluents Throughout the U.S.: The objective of this project is the attempt to relate actual WWTP design, operation and character of waste treated to the endocrine activity of the effluent. Such a relationship will provide insight into why some WWTPs appear to treat EDCs effectively while other plants apparently do not. In collaboration with ORD's National Exposure Research Laboratory (NERL), 50 effluents were sampled and measured for reproductive hormones and overall estrogenicity using a fish vitellogenin bioassay.
The results of this research can be used to help WWT operators understand the capability of their plants to remove EDCs, how process variables influence performance, and how to improve the operation of their plants to minimize effluent levels of EDCs. In the future, if EPA concludes that EDCs in effluents must be regulated, the Office of Water will require performance information on conventional and innovative treatment to make regulatory determinations.
- The timeframe for this work to be completed is estimated to be six years. Collectively, this research will provide a much clearer picture as to the potential for WW effluents to contribute EDCs to the environment, and whether innovative risk management steps are required managing this source to the environment.
Marc Mills at email@example.com